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Isolation and Identification of v-Tetrazine Derivatives on Decomposition of Nitrosamine Anions.

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C 0 M M U N I C AT1 0N S
Isolation and Identification of v-Tetrazine
Derivatives on Decomposition of
Nitrosamine Anions‘**]
By Dieter Seebach, Dieter Enders, Bernd Renger,
and Werner Briigel[*]
Dedicated to Professor F. Krohnke on the occasion
of his 70th birthday
Hitherto there has been no compound with an established
v-tetrazine structure“’ in which four contiguous nitrogen
atoms are incorporated into an aromatic ( I ) , partially
[e. g. (2)] or fully hydrogenated six-membered ring; tetrahydro derivatives (2) would be particularly interesting
for comparison with the well known, open-chain 2-tetrazenes (3) of trans configuration, as possible inverse dienophiles, and as precursors for preparation of diazetidines
(4).
We have now found that the N-oxides ( 5 a ) , (5b), and
( 5 c ) , respectively, can be isolated as decomposition products of metalated nitrosaminest2] (dimethylnitrosamine,
methylcyclohexylnitrosamine, and 1-nitrosopiperidine) in
30% -45% yields and can be reduced quantitatively by
trimethyl phosphite to the oxygen-free compounds ( 6 a ) ,
( 6 b ) , and ( 6 c ) , respectively. Proof of the structures of
the new compounds (C, H, and N contents within 0.3%,
osmometric molecuiar weights within 5% of the theoretical
values) rests on spectroscopic studies: The mass spectra
of ( 5 a ) - ( 5 c ) show an ( M - O ) , and ( 6 c ) an (M-N,)
line. In the NMR spectrum (CDCI,) the presence, for
example, of C, symmetry only in ( 5 a ) is evident from
the appearance of two CH3 singlets (6=2.92 and 3.08
ppm) and an AA’BB multiplet (3.3 ppm) for the CH2
groups, whilst ( 6 a ) shows a 6H (3.05 ppm) and a 4 H
singlet (3.12 ppm). In the UV region (CH,OH) (5a)-(5c)
have Lax
=288-294nm (log&=4.08), and the tetrahydrov-tetrazines (6a)-(6c), like 2-tetrazenes (3), have two
maxima [270-280
(log E = 3.7) and 220-225 nm
(log&z3.4)]. The IR spectra contain intense bands in the
region characteristic for azoxy (1480 and 1300cm- I ) and
azo compounds (1450cm- ‘). In the Nls-ESCA spectrum
of ( 5 c) the ionization typical[31ofazoxy-N atoms is present
at 403 eV, whereas the reduced ( 6 c ) shows only a relatively
sharp band at 399eV. Finally, Nelsen and Fibingevl4’
obtained ( 6 a ) independently in 4 % yield by oxidation
ofthe bishydrazine (7), and the two samples were identical.
The route by which the oxides ( 5 ) are formed from the
nitrosamines is at present under study; above -80°C
the solutions of the lithium derivatives‘’] give intense ESR
signals. Hence we are certain that decomposition occurs
by way of radicals.
Received. December 29, 1972 [Z 784 IE]
German version: Angew. Chem. 85,504 (1973)
Publication delayed at authors’ request
[l] This structure has been disproved for many of the compounds that
were considered to be c-tetrazines in the earlier literature [ V . P. Wvstruch,
Heterocycl. Compounds 8, 106 (1967)l. We thank Prof. Dr. S. Hiinig,
Prof. Dr. A. R. Karritzkj,and Dr. V P. Wystrach for pertinent information.
[2] D.Serbach and D.Endrrs, Angew Chem. 84, 350, 1186. I 1 87 (1972):
Angew. Chem. internat. Edit. 1 1 , 301, 1101, I102 (1972).
[3] K . Siegbahn et a/., Nova Acta Regiae SOC.Sci. Upsal. [4], 20 (1967).
[4] S. F . Nelsen and R. Fibiger, J. Amer. Chem. SOC.94, 8497 (1972).
We thank them for supplying us with a copy of the manuscript prior
to publication.
8-Quinolinecarboxylic Acid from
3,l-Benzoxazin-4ones and Enamines
By WoCfgang Steglich and Oswald Hollitzerp]
“=I4
f5a), m. p. 59.5-60.0 C
f5b). m. p. 83.0-84.5 ’C
( S c ) , m. p. 79.5 ‘C
“=rj
(6~).b. p. 85”C/10 torr
(661, dec. 92-94 C
f6c), m. p. 67°C
[*I
Prof. Dr. D. Seebach. Dip).-Chem. D. Enders, and B. Renger
Institut fur Organische Chemie, Fachbereich Chemie der Universitat
63 Giessen, Ludwigstrasse 21 (Germany)
Dr. W. Briigel
Hauptlaboratorium der Badischen Anilin- & Soda-Fabrik A C
67 Ludwigshafen (Germany)
[**I This work was supported by the Dcutsche Forschungsgemelnschaft
and the Fonds der Chemischen Industrie. D. E. thanks the Studienstiftung
des Deutschen Volkes for a grant.
Angew. Chem. internat Edit.
1 Val. I 2 (1973) 1 NO.6
3,1-Benzoxazin-4-ones and ynamines afford 4-(dialkylamino)quinolines and 3,3-disubstituted 4(3H)-quinolones”’. With enamines the reaction takes a different
course: the CO, group is retained and 8-quinolinecarboxylic acids such as (3) and ( 4 ) are formed.
If the 2-(trifluoromethyl)-3,1-benzoxazin-4-ones
(1 a ) to
( I c ) [ l ]are treated in ether or acetonitrile with N,N-diethylI-butenamine, the diethylammonium salts (2) of the 8quinolinecarboxylic acids are precipitated after a short
time; these salts are filtered off and partitioned between
1 N N a O H and ether, the free acids (3) being obtained
by acidifying the aqueous phase. The mother liquor remaining after isolation of (2) contains varying amounts of
the diethylamides ( 5 ) of N-(trifluoroacety1)anthranilic
[*J Prof. Dr. W. Steglich and DipLChem. 0 Hollitzer
Organisch-Chemisches Institut der Technischen Universitit
I Berlin 12, Strasse des 17. Juni 135 (Germany)
495
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decompositions, isolation, nitrosamines, anion, identification, tetrazine, derivatives
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